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Zhou S, Huang P, Wang L, Hu K, Huang G, Hu P. Robust changes in global subtropical circulation under greenhouse warming. Nat Commun 2024; 15:96. [PMID: 38167831 PMCID: PMC10762120 DOI: 10.1038/s41467-023-44244-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
The lower tropospheric subtropical circulation (SC) is characterized by monsoons and subtropical highs, playing an important role in global teleconnections and climate variability. The SC changes in a warmer climate are influenced by complex and region-specific mechanisms, resulting in uneven projections worldwide. Here, we present a method to quantify the overall intensity change in global SC, revealing a robust weakening across CMIP6 models. The weakening is primarily caused by global-mean surface warming, and partly counteracted by the direct CO2 effect. The direct CO2 effect is apparent in the transient response but is eventually dominated by the surface warming effect in a slow response. The distinct response timescales to global-mean warming and direct CO2 radiative forcing can well explain the time-varying SC changes in other CO2 emission scenarios. The declined SC implies a contracted monsoon range and drying at its boundary with arid regions under CO2-induced global warming.
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Affiliation(s)
- Shijie Zhou
- Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
| | - Ping Huang
- Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China.
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China.
| | - Lin Wang
- Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China.
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China.
| | - Kaiming Hu
- Center for Monsoon System Research, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
| | - Gang Huang
- State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
- Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, 266237, Qingdao, China
| | - Peng Hu
- Department of Atmospheric Sciences, Yunnan University, 650500, Kunming, China
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Hofmann GS, Silva RC, Weber EJ, Barbosa AA, Oliveira LFB, Alves RJV, Hasenack H, Schossler V, Aquino FE, Cardoso MF. Changes in atmospheric circulation and evapotranspiration are reducing rainfall in the Brazilian Cerrado. Sci Rep 2023; 13:11236. [PMID: 37433851 PMCID: PMC10336145 DOI: 10.1038/s41598-023-38174-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 07/04/2023] [Indexed: 07/13/2023] Open
Abstract
Here we analyze the trends of rainfall and the frequency of rainy days over the Brazilian Cerrado between 1960 and 2021 in four distinct periods according to the seasonal patterns over the region. We also evaluated trends in evapotranspiration, atmospheric pressure, winds, and atmospheric humidity over the Cerrado to elucidate the possible reasons for the detected trends. We recorded a significant reduction in rainfall and frequency of rainy days in the northern and central Cerrado regions for all periods except at the beginning of the dry season. The most pronounced negative trends were recorded during the dry season and the beginning of the wet season, where we recorded reductions of up to 50% in total rainfall and the number of rainy days. These findings are associated with the intensification of the South Atlantic Subtropical Anticyclone, which has been shifting atmospheric circulation and raising regional subsidence. Moreover, during the dry season and the beginning of the wet season, there was a reduction in regional evapotranspiration, which also potentially contributed to the rainfall reduction. Our results suggest an expansion and intensification of the dry season in the region, potentially bringing broad environmental and social impacts that transcend the Cerrado boundaries.
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Affiliation(s)
- G S Hofmann
- Programa de Pós-Graduação em Geografia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
- Laboratório de Geoprocessamento, Centro de Ecologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | - R C Silva
- Programa de Pós-Graduação em Geografia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - E J Weber
- Departamento Interdisciplinar, Universidade Federal do Rio Grande do Sul, Tramandaí, RS, Brazil
- Programa Pós-Graduação em Sensoriamento Remoto, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - A A Barbosa
- Earth System Sciences, National Institute for Space Research, Instituto Nacional de Pesquisas Espaciais, São José Dos Campos, SP, Brazil
| | - L F B Oliveira
- Departamento de Vertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - R J V Alves
- Departamento de Botânica, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - H Hasenack
- Laboratório de Geoprocessamento, Centro de Ecologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
- Programa de Pós-Graduação em Agronegócios, Centro de Pesquisas em Agronegócios, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - V Schossler
- Programa de Pós-Graduação em Geografia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - F E Aquino
- Programa de Pós-Graduação em Geografia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - M F Cardoso
- Earth System Sciences, National Institute for Space Research, Instituto Nacional de Pesquisas Espaciais, São José Dos Campos, SP, Brazil
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Carpenedo CB, Ambrizzi T, Silva RC. Sea ice in the Weddell Sea and its relationship with the South Atlantic Subtropical High and precipitation in South America. AN ACAD BRAS CIENC 2022; 94:e20211623. [PMID: 36287464 DOI: 10.1590/0001-3765202220211623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 07/25/2022] [Indexed: 11/30/2022] Open
Abstract
This study aims to evaluate the position and intensity of the South Atlantic Subtropical High (SASH), related to sea ice extent (SIE) retraction and expansion in the Weddell Sea, assessing precipitation in South America. We assess the difference between atmospheric fields related to SIE (four most intense retraction events minus four most intense expansion events) in February. To this end, we used NSIDC SIE, ERA-5 reanalysis, CHIRPS precipitation, ICOADS SST, ONI/SAM indexes (CPC/NOAA). In the following month, under neutral ENSO and SAM, we observed tropospheric warming in the Weddell Sea and cooling in the mid-latitudes South Atlantic. There is a weakening of both the Weddell Sea circumpolar low and the high pressures between tropical and subtropical latitudes, in addition to the equatorward shift of the Ferrel cell. Therefore, SASH weakens and contracts, resulting in a reduction of the tropical Atlantic moisture supply to South America and negative precipitation anomalies in the tropical region - similar to the suppression pattern of the South Atlantic Convergence Zone. Our results suggest that SIE retraction (expansion) in the Weddell Sea may contribute to the weakening (strengthening) of the SASH and an early-ending (longer-ending) or drier-ending (wetter-ending) rainy season in tropical South America.
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Affiliation(s)
- Camila B Carpenedo
- Universidade Federal do Paraná, Setor de Ciências Agrárias, Departamento de Solos e Engenharia Agrícola, Rua dos Funcionários, 1540, Cabral, 80035-050 Curitiba, PR, Brazil
| | - Tércio Ambrizzi
- Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Departamento de Ciências Atmosféricas, Rua do Matão, 1226, Cidade Universitária, 05508-090 São Paulo, SP, Brazil
| | - Rafael Cesar Silva
- Programa de Pós-Graduação em Geografia, Universidade Federal do Rio Grande do Sul, Instituto de Geociências, Av. Bento Gonçalves, 9500, Agronomia, 91501-970 Porto Alegre, RS, Brazil
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Simmonds I, Li M. Trends and variability in polar sea ice, global atmospheric circulations, and baroclinicity. Ann N Y Acad Sci 2021; 1504:167-186. [PMID: 34313329 DOI: 10.1111/nyas.14673] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 06/26/2021] [Accepted: 07/11/2021] [Indexed: 11/28/2022]
Abstract
We analyze the polar sea ice distribution and the global sea level pressure (SLP) and baroclinicity distributions over the "satellite" period of 1979-2020. In the Arctic, there are statistically significant sea ice extent (SIE) decreases in all calendar months, and the annual mean has lost 2.22 million km2 over the four decades. The Antarctic SIE, in marked contrast, increased up to 2014, then commenced a remarkable retreat (the annual mean ice extent decreased by 2.03 million km2 in the 3 years to 2017), and subsequently increased to near its long-term average value in 2020. The shifts in seasonal-mean SLP patterns are consistent with a warming planet. At the synoptic scale, we diagnose the changes in the baroclinicity, the mechanism by which cyclones, fronts, and other weather systems are generated. Through a novel presentation, we give an overview of the relative roles of changes in the vertical shear and static stability in influencing the global trends in baroclinicity. In both the Arctic and Antarctic regions, baroclinicity is shown to have increased in each season (with the sole exception of the Arctic in summer). This increase, coupled with midlatitude decreases in baroclinicity, results in poleward shifts of the storm tracks.
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Affiliation(s)
- Ian Simmonds
- School of Earth Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Muyuan Li
- School of Earth Sciences, The University of Melbourne, Parkville, Victoria, Australia.,CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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Increasing risk of another Cape Town "Day Zero" drought in the 21st century. Proc Natl Acad Sci U S A 2020; 117:29495-29503. [PMID: 33168753 DOI: 10.1073/pnas.2009144117] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Three consecutive dry winters (2015-2017) in southwestern South Africa (SSA) resulted in the Cape Town "Day Zero" drought in early 2018. The contribution of anthropogenic global warming to this prolonged rainfall deficit has previously been evaluated through observations and climate models. However, model adequacy and insufficient horizontal resolution make it difficult to precisely quantify the changing likelihood of extreme droughts, given the small regional scale. Here, we use a high-resolution large ensemble to estimate the contribution of anthropogenic climate change to the probability of occurrence of multiyear SSA rainfall deficits in past and future decades. We find that anthropogenic climate change increased the likelihood of the 2015-2017 rainfall deficit by a factor of five to six. The probability of such an event will increase from 0.7 to 25% by the year 2100 under an intermediate-emission scenario (Shared Socioeconomic Pathway 2-4.5 [SSP2-4.5]) and to 80% under a high-emission scenario (SSP5-8.5). These results highlight the strong sensitivity of the drought risk in SSA to future anthropogenic emissions.
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